Explanation:
Our Sun is in a continual state of oscillation.
Large patches of the
Sun vibrate in and out, back and forth, even as the
Sun rotates.
One mode of Solar oscillation is depicted graphically
above, with blue indicating outward motion,
and red indicating inward motion.
Although sensitive optical solar observatories can only directly detect surface motions,
they give information about vibrations occurring much deeper in the
Sun.
In helioseismology, these oscillations are
being analyzed and are revealing unprecedented
information about the density, temperature,
motion, and chemical composition of the
entire Sun.